1. Field of the Invention
The present invention relates to a tree structure address setting method for executing automatically addressing for a plurality of relay units connected via a tree structure and a system for embodying the same.
2. Description of the Prior Art
In the prior art, as an address setting method, there has been a method set forth in Patent Application Publication (KOKAI) Hei 8-116578, for example. In this address setting method, each of plural universal head controllers which are connected like a chain receives an address assignment command and an address initial value from an upstream side, then registers a received address value as an own address and increments the address value, and then transmits the incremented address value and the address assignment command to a downstream side. As a result, the addresses of the adjacent relay units can be incremented sequentially.
Further, as a tree structure address setting method, there has been a method set forth in Patent Application Publication (KOKAI) Hei 7-123052, for example. In this address setting method, addresses which are ordered hierarchically by designating a management unit as an uppermost layer are assigned previously to the management unit and all relay units, and addresses equivalent to the above addresses assigned to the management unit and the relay units in the uppermost hierarchy out of plural interconnectable relay units are set automatically to modems respectively.
Furthermore, as a terminal address automatic setting method, there has been a method set forth in Patent Application Publication (KOKAI) Hei 5-176378, for example. In this method, addresses are set by using time as a variable.
In addition, an address setting method for a communication system including serial connections and branch connections, there has been a method set forth in Patent Application Publication (KOKAI) Hei 8-18579, for example. In this method, a base station calls mobile sets, which are positioned in one connection column of the serial connections or branch connections, sequentially in the order in which the mobile set is positioned closer to a base station. If a response is returned from the mobile set, the base station transmits an address setting signal to the concerned mobile set so as to set an address in the concerned mobile set and such procedure is repeated. On the contrary, if no response is returned from the mobile set, the base station then calls the mobile sets, which are positioned in other connection column of the serial connections or branch connections, in the order in which the mobile set is positioned closer to the base station, and then the base station transmits the address setting signal to the mobile set which has sent out the response so as to set the address in the concerned mobile set.
However, the method set forth in Patent Application Publication (KOKAI) Hei 8-116578 has disclosed the address setting method for the relay units which are connected like a chain and the method set forth in Patent Application Publication (KOKAI) Hei 8-18579 has disclosed the address setting method for the communication system including serial connections and branch connections, but they have not disclosed an address setting for a plurality of relay units which are connected to have a tree structure.
Conversely, the method set forth in Patent Application Publication (KOKAI) Hei 8-116578 has surely disclosed the tree structure address setting method, but it has not disclosed a method which enables address setting of a plurality tree structure relay units automatically in a short time at all.
In addition, in the method set forth in Patent Application Publication (KOKAI) Hei 5-176378, the sequence of the addresses cannot be predicted. Therefore, in a complicated system which includes a large number of relay units, it is anticipated that the address setting in respective relay units becomes difficult.